This project will study the interaction between cellular and humoral immune factors within malignant gliomas, neoplasms of the central nervous system. Specifically, infiltrating T lymphocytes, B lymphocytes and macrophages will be localized immunohistologically within the tumors. Tumorassociated immunoglobulin will be localized immunohistologically, and its distribution with respect to the infiltrating host cells as well as neoplastic cells will be characterized. Cells expressing receptors for the Fc portion of IgG will be localized, and the interaction of immunoglobulin with the cells will be characterized. The nature of the Fc receptor-associated immunoglobulin, i.e., cytophilic antibody or antigen-antibody complexes, will be assessed. Finally, one potential functional effect of the interaction between immunoglobulin and Fc receptor-positive cells, blockade of antibody-dependent cellular cytotoxicity, will be studied. The potential significance of the study rests in the exploration of possible tumor-associated mechanisms for immunosuppression promoting tumor progression.